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A genuine second wave looks to have arrived in Northeastern metros apart from NYC; the synchrony looks to me sufficient that this would be driven by seasonality and sun-exposure rather than spread. Recommend taking Vitamin D3 if you are not already.
This study found (among fairly light-skinned participants) that at the latitude of Boston D3 synthesis ended in November, at latitude of Edmonton (ie, Europe) in October. https://mobile.twitter.com/toad_spotted/status/1322877934122815488
Seasonality is *the* dominant factor in respiratory viruses and related deaths. This discussion of influenza seasonality D-regulation is fascinating,suggests these patterns have deep physiological causes that go beyond transmission being easier inside. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2279112/
Again, when it comes to influenza, these aren't minor fluctuations, it's the whole thing. This is a different/novel virus and not a flu but we can expect some commonality. https://mobile.twitter.com/RCAFDM/status/1323052000871895040
There may also be other relevant physiological factors associated with sun exposure that have an effect on SARS2- nitric oxide may also be involved, and is harder to supplement for, though I believe L-Arginine is a precursor. https://mobile.twitter.com/toad_spotted/status/1253674730361626624
There are other potential sources of racial disparities in severity- this thread talks about one that has subsequently been bourne out (IL-6:IL-10 ratios are used in diagnosis now) but if you are darker skinned VitD deficiency may be especially important https://mobile.twitter.com/toad_spotted/status/1246489391335342080
And latitude rather than temperature appears to partly explain why Europe has had both its waves ahead of the US https://mobile.twitter.com/__ice9/status/1323570070895923201
At least one measure that shouldn't be driven by testing- sewage viral concentration- looks comparable in Boston to the spring, but this doesn't appear to be the case for deaths or hospitalizations.
